How to create a query for items that appears only in one list - sql

Question

The scenario I am working on is as follows:-
A number of interviews are conducted a food poisoning case
A query called qryFoodInCase ( fldCaseID, fldFood) is generate consisting of all the food mentioned in all the interviews
An other query call qryFoodInInterview( fldCaseID, fldInterviewID, fldFood) consist of the food mentioned in each Interview
Now I am after the sql for a query that will return the food that was not consumed by an interviewee but consumed by one or more other interviewees.
The closest I've got is:
select Q1.fldCaseID,Q1.fldfood,Q2.fldInterviewID,fldGotSick
from qryFoodInCases as Q1
left join
(select * from qryFoodInInterview where qryFoodInInterview.fldInterviewID=1) as Q2
on Q1.fldFood=Q2.fldFood
where Q1.fldCaseID=1
The field Q2.fldInterviewID returns 1 for the food consumed and null for the food not consumed. However, I don't want to hard code the fldInterviewID in the sql. I would like a similar recordset returned for all the interviews in one query.
The SQL for qryFoodInCase and qryFoodInInterview are as follows:-
CREATE VIEW `qryFoodInCases`
AS
SELECT tblCases.fldCaseID
,fldfood
,count(tblFoodHistory.fldFoodID) AS fldFoodFrequency
FROM tblFood
INNER JOIN tblFoodHistory
ON tblFoodHistory.fldFoodID = tblFood.fldFoodID
INNER JOIN tblMealHistory
ON tblFoodHistory.fldMealID = tblMealHistory.fldMealHistoryID
INNER JOIN tblInterviews
ON tblInterviews.fldInterviewID = tblMealHistory.fldInterviewID
INNER JOIN tblCases
ON tblCases.fldCaseID = tblInterviews.fldCaseID
GROUP BY tblCases.fldCaseID, tblFood.fldFood
OUTPUT:
+-----------+------------+------------------+
| fldCaseID | fldFood | fldFoodFrequency |
+-----------+------------+------------------+
| 1 | Banana | 3 |
| 1 | Beans | 5 |
| 1 | Cabagge | 3 |
| 1 | Chicken | 1 |
| 1 | Pork | 5 |
| 1 | Potatoes | 1 |
| 1 | Rice | 1 |
| 1 | fried fish | 1 |
| 2 | Cabagge | 1 |
| 2 | Chicken | 2 |
| 2 | Potatoes | 1 |
| 2 | Rice | 1 |
| 2 | Salad | 1 |
+-----------+------------+------------------+
and
CREATE VIEW `qryFoodInInterview`
AS
SELECT tblInterviews.fldCaseID
,tblInterviews.fldInterviewID
,tblFood.fldFood
,tblInterviews.fldGotSick
FROM tblInterviews
INNER JOIN tblMealHistory
ON tblInterviews.fldInterviewID = tblMealHistory.fldInterviewID
INNER JOIN tblFoodHistory
ON tblFoodHistory.fldMealID = tblMealHistory.fldMealHistoryID
INNER JOIN tblFood
ON tblFood.fldFoodID = tblFoodHistory.fldFoodID
GROUP BY tblInterviews.fldInterviewID, tblFoodHistory.fldFoodID
OUTPUT
+-----------+----------------+------------+------------+
| fldCaseID | fldInterviewID | fldFood | fldGotSick |
+-----------+----------------+------------+------------+
| 1 | 1 | Pork | 0 |
| 1 | 1 | Banana | 0 |
| 1 | 1 | Rice | 0 |
| 1 | 1 | Potatoes | 0 |
| 1 | 2 | Chicken | 1 |
| 1 | 2 | Banana | 1 |
| 1 | 2 | Beans | 1 |
| 1 | 4 | Pork | 1 |
| 1 | 4 | fried fish | 1 |
| 1 | 4 | Beans | 1 |
| 2 | 6 | Salad | 0 |
| 2 | 6 | Chicken | 0 |
| 2 | 6 | Cabagge | 0 |
| 2 | 6 | Rice | 0 |
| 2 | 6 | Potatoes | 0 |
| 1 | 8 | Pork | 0 |
| 1 | 8 | Cabagge | 0 |
| 1 | 9 | Pork | 1 |
| 1 | 9 | Banana | 1 |
| 1 | 9 | Beans | 1 |
| 1 | 10 | Cabagge | 1 |
| 1 | 10 | Beans | 1 |
| 1 | 11 | Pork | 1 |
| 1 | 11 | Cabagge | 1 |
| 1 | 11 | Beans | 1 |
+-----------+----------------+------------+------------+

Answer 1

SQL Fiddle Demo
create a cross join off all food with all interviewrs
then a left join to see which one didnt had interview
the null mean interview didnt consume food
and exists mean someone different to interview consume food
.
SELECT F.fldFood, I.fldInterviewID, FI.fldInterviewID
FROM qryFoodInCases F, (SELECT DISTINCT fldInterviewID FROM qryFoodInInterview) I
LEFT JOIN qryFoodInInterview FI
ON F.fldFood = FI.fldFood
AND I.fldInterviewID = FI.fldInterviewID
WHERE FI.fldInterviewID IS NULL
AND EXISTS (SELECT 1
FROM qryFoodInInterview Q1
WHERE Q1.fldFood = F.fldFood
AND Q1.fldInterviewID <> I.fldInterviewID)
;
The trick was do the thing one step at the time. Once I realize I need all the combinations and create the cross join, the rest was easy.

Answer 2

select Q1.fldCaseID,Q1.fldfood,Q2.fldInterviewID,fldGotSick
from qryFoodInCases as Q1
left join
(select * from qryFoodInInterview QF1
JOIN qryFoodInInterview QF2
where QF1.fldInterviewID <> QF2.fldInterviewID
AND QF1.fldInterviewID > QF2.fldInterviewID
) as Q2
on Q1.fldFood=Q2.fldFood
where Q1.fldCaseID=1
As you mentioned you want to duplicate the items FoodInterviews, self JOIN will suffice your question. Please try this out , caution I didn't tested it.
Fixing Missed Self Join Condition to fix duplicates.